1. Field of the Invention
The present invention relates to a joint device for connecting two members which are incorporated in an apparatus and which can rotate relative to each other.
2. Description of the Related Art
A laptop word-processor or a laptop personal computer comprises a main body and a rotatable display unit. The display unit is attached at one side to the main body by a hinge mechanism and is therefore rotatable. Once the unit is bent down onto the main body, it is held in a closed position by means of a lock mechanism.
The hinge mechanism includes a friction member which applies a friction force on the display unit which has been opened, thereby holding the unit at a desired angle relative to the main body. The hinge mechanism may also include a spring which exerts a return torque on the display unit immediately after the unit has been moved up a little from the closed position, thereby quickly rotating the unit upward until the unit reaches a position where it is inclined to the main body at a predetermined angle.
Recently it is increasingly demanded that the laptop apparatuses be made thinner. The thinner they become, the less space is provided for accommodating the hinge mechanism. Hence, it is required that the friction member and the spring be as small as possible. If the friction member and the spring are as small as desired, they may fail to generate an adequate friction force and a sufficient return torque, respectively.